1. Field of the invention
The present invention relates, in general, to the field of catalysis for the reduction of emissions from internal combustion engines and, more particularly, to a quick-heating catalytic converter, which enables the exhaust generated immediately after engine starting to be heated to the temperature sufficient for the catalyst to function optimally within seconds.
2. Description of the Prior Art
As long as vehicles, such as passenger cars, autotrucks and the like, burn petrochemical products to produce drive power, exhaust gases are generated, which generally contain pollutants as a consequence of the combustion in the internal engines. With recent advances in the controlling apparatuses of exhaust gases, most of the pollutants can be converted into harmless materials, generally CO.sub.2 and H.sub.2 O, prior to emission from a tail pipe of a muffler.
An apparatus for controlling exhaust gases is a complex assembly consisting of mechanical and electronic parts, which are designed to function to neutralize exhaust gases in concert with each other, thereby reducing the harmful pollutants contained therein. Of them, a catalytic converter is the most well known, which takes advantage of a catalyst, which alters the velocity of the chemical reaction and may be recovered essentially unaltered in form and amount at the end of the reaction.
Most of the unacceptable emissions or pollutants created by internal combustion engines equipped with catalytic converters occur during cold start operations. These pollutants are emitted in the first five minutes after cold engine starting.
As the governmental requirements of the U.S.A. regarding acceptable emission levels become more strict, research of vehicle manufacturers has been and continues to be directed to the development of various fuels which do not produce unacceptable emissions or pollutants.
As a result, electric vehicles were developed, and hydrogen, natural gas, methanol, ethanol and reformulated gas are used as fuels or taken into consideration. However, all of them suffer from drawbacks. For example, electric vehicles themselves are completely pollution-free, but if all of the currently used cars were required to be electrically charged for fueling, the capacity of the current power plants would be increased twice, resulting in aggravation of pollution to the same extent. Another disadvantage of electric vehicles is that it takes too much time to electrically charge them when the existing electric stored energy is not sufficient. Usually, the current electric vehicles should be recharged with electric energy after a use of 1 to 2 hours and the recharging time is too long. Taking these problems into account, world-wide prominent vehicle manufacturers, including the GM company, have invested an enormous amount of money, but the vehicles developed thus far are found not to overcome the above-mentioned problems completely.
In all consideration, gasoline vehicles are thought to be the most economical and convenient, if they are improved in pollution production, because they have been familiar to users for approximately one hundred years.
As mentioned above, the most problematic in the production of pollutants by internal combustion engines is a period of the first five minutes after starting the engine. During this period, the exhaust gas is not controlled by catalytic converters. On the other hand, once the vehicles are driven for an extended period of time, greater than 5 min, the inside of the combustion engines reaches a temperature of about 1,000.degree. C. and the tail pipes of mufflers, from which the exhaust gas is emitted, are heated to about 650-800.degree. C.
At least as high as about 1,000.degree. C. is needed to convert carbon monoxide (CO) into carbon dioxide (CO.sub.2) in the air. The reduction of the temperature with the aid of catalysts is the essence of the catalytic converter techniques of which automobile manufacturers make a current study. Indeed, the temperature at which the neutralization of carbon monoxide into carbon dioxide in the air occurs, can be reduced to 190.degree. C. when copper-based catalysts (sometimes added with chrome) are used.
The predominant emission-controlling techniques in use by the automobile manufacturers are three-way catalytic converters which have been developed from two-way catalytic converters in order to neutralize nitrogen oxides (NO.sub.x).
The automobiles equipped with the three-way converters may be said to be almost pollution-free. However, because, from the year 2002, there will be enacted an anti-pollution law which prescribes the automobiles should be completely pollution-free, various alternatives are now being developed by automobile manufacturers.
In present, the control and suppression of unwanted emissions created by the operation of an internal combustion engine follows the technique which Corning of the GM company developed. As high as 96% of the pollutants contained in emissions can be removed by use of the catalytic converter of Corning. The reason why the pollutants or unwanted emissions cannot be removed completely is that the exhaust gas created immediately after engine starting has a temperature of 52.degree. C. (126.degree. F.) or less at which the catalyst cannot function chemically.